This paper summarizes the test recommendations for in situ assessment of structural timber using stress wave measurements as developed by members of the RILEM Technical Committee AST 215 “In-situ assessment of structural timber”. In the first part, the basic principles, the equipment, and the practical application of stress-wave-based testing using the time-of-flight method are described. A detailed testing procedure provides hands-on information on the execution of in-field stress wave testing. A typical example is given to demonstrate step-by-step on how to evaluate stress wave readings and the health state of the inspected timber member. The latter part of the paper gives a short overview of the use of acoustic tomography and ultrasonic echo methods.